There are three options in these types of cases. Which gets done is pretty much up to you.
1. You can propose moving it to the correct entry, if you know what it is.
2. You can propose moving it to the general iris category: (
Irises (Iris) (this option also allows you to easily move it to the correct entry some time in the future, if its identity becomes known)
3. You can propose to delete it.
It's your decision what to do because you, of course, own picture. I will eventually delete it if it's left in the current entry, but generally wait a couple of weeks or so to give people time to decide what they want to do.